1. Field of the Invention
This invention relates to a coiler-furnace unit comprising a coiler having a heatable coiler mandrel, which is disposed in a heat insulating housing, strip guiding means comprising pressure applying rollers for engaging a strip to be coiled and at least two cylindrical guide shoes extending, around and engageable with the coiler mandrel.
2. Description of the Prior Art
In order to reheat a strip to be rolled to a temperature which is sufficient for the rolling operation, coiler-furnace units for reheating the strip to a sufficiently high temperature are provided before and behind the reversing stands of a hot rolling plant. Austrian Pat. No. 370,776 discloses a strip guiding means for assisting the coiling of the strip in the coiler-furnace unit on the collar mandrel, which is disposed in a heat insulating housing. The strip guiding means comprises pressure applying rollers for engaging the strip to be coiled as well as two cylindrical guide shoes, which extend around the coiler mandrel and are secured to rockers. The rockers extend outside the heat insulating housing and are pivoted on axes which are parallel to the coiler mandrel. The rockers are operable to move the guide shoes into engagement with the coiler mandrel from opposite sides. As a result, the leading end of the strip, which has been introduced into the coiler-furnace unit over a strip guiding bridge, is forced against the coiler mandrel by the pressure applying rollers and is guided around the coiler mandrel by the guide shoes. The strip coiled on the coiler mandrel may be heated, e.g., by hot gases, which are introduced into the heat insulating housing. But such a heating by means of hot gases will promote the formation of scale and the resulting scale will be trapped between the convolutions of the coiled strip and will subsequently be rolled into the strip. In order to avoid said disadvantage it is known from Austrian Pat. Nos. 373,290 and 370,777 to heat the coiler mandrel and to use it as a heater for heating the coiled strip so that the coiled strip being formed will be heated from the inside.
The pressure applying rollers engaging the coiled strip on the outside and the guide shoes extending around the coiled strip will be subjected to a high heat load, regardless of the manner in which the strip is heated, and will dissipate a part of the heat which is supplied. This increases the energy requirement and adversely affects the uniform heating of the coiled strip, particularly if it is heated from the coiler mandrel.